Hello, this patcher has two [expr] objects that approximate the behavior of the gain~ object. Gain controls tend to use logarithmic scaling. What scalar formula does the incoming OSC have?
[atodb] and [dbtoa] may also be helpful.

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OK, The scalar stuff has to do with the way volume (also known as gain or amplitude) is processed by whatever is transforming incoming numbers (or signals) into other numbers (or signals) to outgoing numbers. The main things to consider are:
when you write: One of my application has a master volume with a range of -90 ( -inf ) and +10 but it sends a float so -90 = 0. and +10 = 1.
First of all, is this application a max app? if so, what object(s) are used to generate the -90 to +10 range?
If it’s not a Max app, what is it?
If the value is an "incoming osc value" what is it addressing within Max? if the goal is to scale the -90 +10 to a number that can be used to set the settings of [gain~] try this quick way:

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Yes that’s clearer. Without seeing the output of the Cue Station fader values I can’t help with the scaling. Maybe someone on this forum knows.
If [atodb] doesn’t match the Cue Station it may be a matter of playing with numbers in [exp] or [linedrive] until a close match is found…